Target Component

The specification of the Target component differs somewhat depending on whether a Natural Guide Star (NGS) or the Laser Guide Star (LGS) is being employed. There also can be differences in the target component, depending on whether NIRI or NIFS is being used, since the NIFS OIWFS can be employed to provide tip/tilt information.

When a NGS is used, the coordinates of the NGS (either those of the target itself if it is being used as the NGS, or those of a nearby star) must appear in the target component as AOWFS-1, below the "Base" coordinates, as follows.

If the LGS is used, one must specify the tip/tilt star as AOWFS-1.

For NIFS, one may also specify this star as OIWFS-1 (this has some advantage as any changing flexure between ALTAIR and NIFS is removed). In this case the target component will have three entries: Base, AOWFS-1, and OIWFS-1, with the coordinates of the last two being identical.